Linde LLCAmerica’s appetite for cookies continues to grow with a proliferation of baked and refrigerated dough choices in the grocery aisle. Plus, cookies abound in a growing number of restaurants, foodservice establishments, malls, retail chains, convenience stores and online sites. Production of private-label cookies in the U.S. now tops more than $1B per year.
Rapid chilling and temperature control during dough processing is critical for enhanced product quality as bakeries scale up, develop new cookie sensations or expand into new markets. To meet these needs, in-line cryogenic chilling and freezing processes, which use either liquid carbon dioxide (CO2) or liquid nitrogen (N2), can offer significant advantages in increased production throughput, space and lower operating costs over other chilling or freezing methods. They can play an important role whether doughs are sliced and formed at the factory, baked and packaged for sale, sold as refrigerated raw dough or fully frozen for shipment.
Pre-Chilling Dry Ingredients
Even before cookie dough is mixed, cryogenic technology can help boost process quality by chilling flour, sugar or other dry ingredients as they are conveyed from silo to mixer. Ingredient temperatures inside silos can vary widely — not just during the warm summer months, but daily — especially for silos exposed to direct sunlight.
State-of-the-art dry ingredient chilling systems can achieve a consistent flour temperature within +/- 1ºF of the desired setpoint at the mixer using a controlled injection of liquid CO2 into the transfer line. This level of control dramatically improves mixer repeatability, especially when compared to the variability associated with traditional water ice or alternative CO2 chilling methods. Cryogenic-injection chilling systems are frequently incorporated when installing pneumatic conveyor systems, or can be retrofitted to existing transfer lines.
In addition to cryogenic chilling systems, in-line cryogenic freezers can improve the handling characteristics of raw cookie dough to speed production and packaging operations. Raw cookie dough can be difficult to smoothly process once the dough is made. Handling and forming of cookie doughs can vary with temperature which can affect the repeatability of product quality, and slicing and stacking operations, especially at higher production volumes.
Freezing Cookie Dough
Cryogenic solutions can be used to either fully freeze or crust freeze cookie dough. The depth of freeze on the dough will depend on the specific production process. For high efficiency, systems must be engineered to apply the desired depth of freeze while optimizing the use of cryogen.
Gluten-free cookie dough may tend to be stickier than other dough. In addition, inclusions — from chocolate morsels to peanut butter chunks — can add to process variability. The temperature of soft or refrigerated dough can also change while being conveyed to slicing, stacking and packing areas resulting in quality and packaging challenges. Dough crusted to the right temperature is always easier to package, or to slice into “pucks.” Beyond dough ingredients, the moisture levels, shape and thickness of raw cookies are also important factors to consider in selecting and optimizing the cryogenic freezing process.
For sliced or formed cookie dough packed in boxes, a crust freeze can improve stackability to speed processing, resulting in the ability to increase production. While cryogenic tunnel freezers are often used for this purpose, a patented impingement freezer from Linde, for example, can be ideal for crust freezing raw formed cookies at high volume, especially when space is at a premium. The impingement freezer can typically freeze about three to five times as much as a conventional cryogenic or mechanical tunnel freezer in the same linear space while reducing operating costs.
Some production plants are limited by storage space in their holding freezers. By fully freezing raw cookie dough at a controlled rate in-line, the bakery preserves product quality and decreases or eliminates freezer storage time prior to shipment. Cryogenic tunnel or spiral freezers can offer an effective solution. Impingement freezers are available in modular design so lines can be readily extended for higher production rates, though space-saving spiral freezers are preferred when capacity is needed and floor space is limited. Spiral freezers range from entry-level box spirals to state-of-the-art high-efficiency spiral freezers.
Newer cryogenic freezers are typically hygienically designed to minimize areas that can harbor food and bacteria. They may include sloped surfaces to ease drainage, and provide full access for cleaning of all surface areas and maintenance.
Shifting Into Cookie Cryogenics
Cryogenic solutions can contribute to process quality, increased production and food safety in cookie operations. This is not only because of the tight temperature control of raw ingredients, but because food safety also pertains to the cryogens. Suppliers of food-contact gases must manage them as any other food ingredient under Food Safety Modernization Act requirements. Beyond the physical properties of the gas, food safety encompasses the production, distribution and handling of the gases all the way through the supply chain.
Major producers of food- and beverage-grade gases certify production facilities to Global Food Safety Initiative standards, and may have food safety management systems in place. Some also provide quality assurance testing, in addition to hazard analysis and required documentation of food safety audits.
Major suppliers will perform in-plant assessments and work with bakeries to develop optimal solutions. They typically provide operator and plant safety training on installation, and may offer parts and maintenance programs to help keep freezers running smoothly.
